Moisture meter



Omit. 11,1927.

L. W. THOMPSON MOISTURE METER Filed Avril 1925 ILcuRvE DRAWINGVOLTMETER.

DRYER ROLLS.

Invent or- Louis \M Thompson, y aw/hajgwz HIS Attorney.

Patented Oct. ll, 1927.

STATES 1,645,077 PATENT orrica.

LOUIS W. THOMPSON, OF SOHENECTADY, NEW YORK, ASSIGNOB TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

MOISTURE METER.

Application filed April 1, 1925.

In connection with certain manufacturing processes, it is desirable tomeasure continuously the amount of moisture in a material being operatedupon. An in..taiice of this is in the manufacture of paper wherein it isdesirable to mea ure the moisture in the paper as it comes from thedryer rolls.

The object of my invention is to provide an improved moisture meter forcontinuously measuring the moisture in a substance such as paper, forexample, and for a conside'ia tion of what I believe to be novel and myinvention attention is directed to the following description and theclaims appended thereto.

In the drawing, the tigure is a diagrammatic view of a moisture meterembodying my invention,,the same being illustrated as being used tomeasure the moisture in paper coming from the dryer rolls of a papermaking machine.

Referring to the drawing, 1 indicates the dryer rolls of a'paper makingmachine, and 2 indicates the sheet of paper passing between the rolls.Only a short length of paper is indicated in the drawing, but it will beunderstood that paper is continuously passing along between the rolls.

According to the embodiment of my invention illustrated in the drawing,I provide two electrical contacts 3 and 4 between which the paper passeswhich contacts may be of any suitable form. In the resent instancecontact 3 is shown as being in the form of a roller. Contact 4 may be asuitable sliding contact. Contacts 3 and 4 are connected by lead wires 5and 6 to the secondary winding 7 of a transformer 8. The primary winding9 of transformer 8 is connected b a lead wire 10 to one side of a sourceof a ternating cu'rrent potential 11 of suitable voltage, and by a leadwire 12 to a continuously rotating contact arm 13. Contact arm 13 movesover an arcuate resistance 14 which is connected by a lead wire 15 tothe other side of potential source 11. In lead wire 15 is a suitableresistance 16. Contact arm 13' may be continuously rotated by anysuitable means. In the present instance it is shown as beingv rotated bya worm gearing 17 driven by a motor 18 which is connected by lead wires19 to source of alternating current potential 11. Connected ,across therimary winding 9 of transformer 8 by ead wires 20 is a suitableelectrical measuring Serial No. 20,017.

instrument 21, a curve drawing voltmeter being indicated in the presentinstance, this being a satisfactory form of measuring iiistrument touse. In lead wires 20 is a re sistance 22.

The operation is as follows Assume that paper 2 is passing continuouslythrough the dryer rolls 1 and that contacts 3 and 4 are in engagementwith the paper on its opposite sides. Assume also, that the circuit onthe primary winding of transformer 8 ha been open and that it has justbeen closed by contact arm 13 engagin the end of resistance 14, it beingunderstood that the contact arm 13 is being rotated continuously in thedirection of the arrow by motor 18. A potential is now impressed uponcontacts 3 and 4by the secondary winding 7 of transformer 8, but withall of resistance 14 in the circuit of primary winding 9, this potentialis not sufficiently reat to break down the resistance offered by paper2. The circuit on secondary winding .7 is thus open. As contact rm 13continues to move it gradually cuts resistance 14 out of the primarycircuit thus gradually increasing the potential across contacts 3 and 4,and eventually this willreach a value such that it will breakdown theresistance offered by the'paper 2. When this happens there will he asudden rush of current in both the primary and secondary windin s andthe circuits connected to them, andthis will effect a decrease in thedrop in potential across winding 9. The point at w ich this drop inpotential begins will be indicated by the curvedrawing volt meter. Afterthe breakdown of the resistance ofiered by the paper has occurred, thecurrent then flowing will be limited by resistance 16.

Arm 13 continues to move and will finally move from on a ement withresistance 14 whereupon bot t 0 primary and secondary transformercircuits will be opened.

This completes the cycle of o oration, and as arm 13 continues to move tis cycle will be repeated, the arm 13 being rotated at a speed such asto give indications at suitable intervals of time. v

The potential at which the resistance offered by paper 2 breaks down isa measure of the amount of moisture in the pa r, and measuringinstrument 21 may be ca ibrated in terms of moisture or other suitableterms. By observing measuring instrument 21, the

tilt

operative may malts adjustments ct the paper-making machinery such asare desirable.

in accordance with the provisions of the patent statutes, 1 havedescribed the prin ciple of operation of my invention, together with theapparatus which it now consider'to represent the best embodimentthereof, but I desire to have it understood that the apparatus shown isonly iilustrative and that the invention may be carried out by othermeans.

What it claim as new and desire to secure by Letters 'Patent oi theUnited States, is

1. In combination, transformer having a primary windinr and a secondarywinding, a pair of space contacts between which a substance is adaptedto be passed continuously, a circuit connecting said contacts to thesecondary winding, a source of potential, a circuit connecting it to theprimary winding, a fined resistance and a variable resist ance in saidprimary circuit, means connected with said last-named resistance foralternately varying the resistance value thereof and opening saidprimary circuit,

and a measuring instrument connected with the primary circuit,

2. In combination, a pair or spaced contacts between which a substance15 adapted to be passed continuously, a source of alterhating current, anornia- 1y open circuit con necting it to said contacts, a resistance insaid circuit, a contactor ior periodically closing said circuit throughsaid resistance and then gradually cutting such resistance out of thecircuit, and a measuring instrument COD, nected to said circuit,

3. In combination, a transformer having a primary windine and asecondary winding, a pair of space contacts between which a substance isadapted to be passed continuously, a circuit connecting said contacts tothe secondary winding, a source of potential,

a circuit connecting it to the primary winding, means forperiodically-varying the resistance oi" the primary circuit, a measuringinstrument associated with said primary circuit, a current limitingresistance in said primary circuit.

4r. The combination with a pair of spaced contacts adapted to beseparated by a substance passed between them, of means connected withsaid contacts for impressing a voltage thereon to break down theresistance of said substance, said means having a winding through whichit receives electric cur-' first-named means for indicating a suddenchange in current flow thereto accompanying a breakdown of theresistance between the contacts.

' lin witness whereof, I have hereunto set my hand this 31st day ofMarch, 1925.

LOUIS W. THOMPSON.

